The electronics industry has experienced an ever increasing demand for smaller and faster electronic devices which are simultaneously able to support a greater number of increasingly complex and sophisticated functions. Accordingly, there is a continuing trend in the semiconductor industry to manufacture low-cost, high-performance, and low-power integrated circuits (ICs). Thus far these goals have been achieved in large part by scaling down semiconductor IC dimensions (e.g., minimum feature size) and thereby improving production efficiency and lowering associated costs. However, such scaling has also introduced increased complexity to the semiconductor manufacturing process. Thus, the realization of continued advances in semiconductor ICs and devices calls for similar advances in semiconductor manufacturing processes and technology.
As one example, a typical lithography process may include forming a patterned resist layer over a hard mask layer. An etching process may subsequently follow, where the hard mask layer is etched using the patterned resist layer as an etch mask, thereby transferring the pattern to the hard mask layer. Further steps are performed to transfer the pattern to a substrate. As IC dimensions continue to scale down, resist layers have also scaled down, presenting new challenges. In some examples, the resist pattern has become narrower and taller, where such high aspect ratios cause the resist pattern to easily collapse. Additionally, as resist layer thicknesses have decreased, there may not be a sufficient thickness of resist to adequately transfer a resist pattern to an underlying layer. In some aspects, this may be due to an insufficient etching resistance of the resist layer. Various bilayer and multilayer (e.g., tri-layer) resist structures have been used in an effort to implement thin imaging layers which overcome one or more of the problems noted above. However, in at least some cases, removal of one or more layers of such a bilayer or multilayer resist structure may also etch an underlying layer, thereby damaging the underlying layer.
Thus, existing techniques have not proved entirely satisfactory in all respects.